For today's app of the day, we have not one, but three calculators. These calculators are modeled after Texas Instruments' graphing calculator series - TI-83, TI-85 and TI-86. The TI-83 is mainly for statistics and trigonometry, TI-85 is for engineering and computer science and TI-86 is for engineering and calculus.

I installed the TI-86 this morning and so far it has worked perfectly. However there is a little quirk with the UI. The UI has also been designed to look like the real thing. While it is still usable, on my phone's 4-inch screen, the buttons are a bit too small and a little hard to use without really looking for what you are pressing. So, people whose phones have smaller screen might need to watch out.